고분자 탄소 나노복합소재 및 탄소소재의 열화학적 합성 및 물성 연구

Abstract

Chapter 1. Sequential impregnation of a composite of poly(vinyl alcohol) and poly(acrylic acid) (PVA–PAA) into carbon-nanotube fibers (CNTFs) and thermal condensation were investigated as a simple and efficient continuous textile engineering technique to prepare mechanically and electrically reinforced CNTFs. The CNTFs that were physically impregnated with PVA–PAA (PI-CNTF–(PVA/PAA))and the chemically cross-linked CNTF(CL-CNTF–(PVA/PAA)) exhibited tensile strengths that were ~1.6 and ~2.1 times higher, respectively, and Young’s moduli that were ~1.3 and ~2.3 times higher, respectively, than those of direct-spun CNTFs. The electrical conductivity of PI-CNTF–(PVA/PAA) and CL-CNTF–(PVA/PAA) had values that were ~1.5 and ~1.7 times higher, respectively, than that of raw CNTFs. Moreover, the chemically cross-linked networks of CL-CNTF–(PVA/PAA) resulting from the heat treatment enhanced the water resistance of the composite.

Chapter 2. Environmentally begin natural amino acids, especially histidine-derived nitrogen-doped carbon materials were readily synthesized from polycondensation reaction and subsequent carbonization via the stepwise thermolysis process with high yields of 40% even at a high temperature of 1000 oC and the nitrogen-atom contents of around 5 wt%. These materials possessed rolled planar structures as well as thick 2D-like planar structures with specific surface area of 455 m2/g, exhibiting a notable specific capacitance of 58 F/g at current densities of 0.1 A/g and superior stability without deterioration of performance values up to 2000 cycles.

Chapter 3. Heteroatoms-doped graphene has received a great deal of attention due to attractive electronic and catalytic properties for promising applications in the fields of electronics, sensors, and electrocatalysis. Heteroatoms substitution in the graphitic framework also induces unique electronic surfaces or active catalytic sites in graphene due to the difference in electronegativity and atomic size between carbon and heteroatoms. Recently, extending the concept of doped graphenes, there have been significant research attempts to harness synergistic effects in the catalytic activity of graphene by developing multiple doping in graphene structures. This includes dual and triple doping of heteroatoms by incorporating nitrogen and other elements such as phosphorus, boron or sulfur. However, these methods uses chemicals with high toxicity and usually results in the low doped heteroatom contents. Thus, there have been extended investigations on more environmentally friendly and efficient synthesis approaches on the heteroatom-doped graphene materials. In this regard, we have inversitigated natural amino acids as efficient and versatile heteroatom precursors to generate heteroatoms-doped carbon materials. In this work, we have successfully demonstrated synthesis and characterization of heteroatoms doped graphene from pyrolyzed natural amino acids, which contain nitrogen or sulfur atoms in side chain motifs. We proved that the pyrolyzed amino acids are excellent precursors for nitrogen doping in graphene, and the doping nitrogen atoms were originated from both amino unit and side chain of amino acids. Moreover, the amino acids such as Cys or Met could be potential candidates as the multi-elemental dopants such as nitrogen and sulfur.